This invention relates to a method of and an arrangement for controlling return quantities of exhaust in an automatic-ignition, internal combustion engine which is supplied by a camshaft-driven piston, injection pump and which comprises an element for controlling exhaust quantities associated with an exhaust return pipe.
It is known in connection with the control of the return of exhaust gases, that the fuel-to-air ratio can be regulated using a control variable in the form of the quantity of air taken in and can be varied by a throttle valve and determined by an air intake meter. The output quantity of the air intake meter is divided in a control unit by the rotational speed measured at a fuel injection pump. The value thus obtained is compared with a control quantity which corresponds to the position of the quantity regulator of the fuel injection pump and which represents a value for the quantity of fuel to be injected. The position of the quantity regulator of the fuel injection pump is corrected by a positioning element commensurate with the deviation in the two control quantities. Through its position, the throttle valve also influences the quantity of returned exhaust which--with the quantity of intake air throttled--is available for filling the remainder of the cylinders of the internal combustion engine. This known method is very complicated and relatively slow in its control behaviour because, in the event of any change in the position of the throttle valve, the required values are only adjusted after the dead time of the controlled system. Above all, an excessive return quantity of exhaust is in danger of producing a brief, but heavy build up of carbon.
An object of the present invention is to develop a method and an arrangement of the type referred to above such that an operationally effective control of return quantities of exhaust commensurate with requirements can be obtained by relatively simple and reliable measures.